Method for Manufacturing a Three-Dimensional Model by Variable Deposition and Apparatus Used Therein
This invention relates to manufacturing a three-dimensional model (3D model) such as a prototype and a mold, more particularly, to development of variable deposition manufacturing.
One of prevailing method of manufacturing a 3D model comprises shaping a high formative material such a liquid or soft material into a configuration of the 3D model, and then setting the configuration by solidifying the material. Another comprises forming a configuration of the 3D model by depositing a powdered or sheeted material.
Herein, xe2x80x9cSolid Freeform Fabrication (SFF)xe2x80x9d means that manufacturing a 3D model from a metal or non-metal material such as paper, wax or plastic resin by depositing the material with controlled in real time by three-dimensional computer-aided design (3D CAD) data. Recently, various materials including metal powder and metal wire are usable in VDM.
One of conventional SFF is a stereolithography in which repeated are steps of depositing a photopolymer in liquid by a depth of layer, and solidifying at least several portions of the photo-polymer. In the stereolithography, solidification of each layer is conducted by locally shooting a laser beam, or generally illuminating light emitted from an ultraviolet lamp. After forming a desired shape of 3D model with a plurality of solidified layers, the photopolymer should be set. However, the photopolymer may contract, as it is set, whereby the shape of 3D model is distorted. If the 3D model has an elongate extension, furthermore, since the extension formed of solidified polymer before setting may drop down due to weight of itself, it is required to support it by a pole. Moreover, most kinds of photopolymer have not enough strength even after setting to be used in an operational constituent.
SFF using a powdered material can be exemplified by a selective laser sintering (SLS) method, which is used by DTM Co., and a three-dimensional printing (3D printing) method, which is used by SOLINGEN Co. and Z Corp.
The SLS method comprises depositing a layer of plastic powder, and fusing the plastic powder by shooting a laser beam. The SLS method is often used in manufacturing a metal article or a mold from metal powder with plastic material coated thereon.
The SLS method needs steps of removing the plastic material from the metal powder, and then sintering the metal powder to be merged into one body. Furthermore, it requires an additional step of infiltrag melted copper into gaps among grains of metal powder. There may be contraction and/or deformation due to heat during copper infiltrating, whereby it is very difficult to get the precise size of the article or mold.
The 3D printing method comprises depositing a layer of powdered material, and then selectively applying a combining agent in liquid thereon. The 3D printing method is used in manufacturing a ceramic shell from ceramic powder, which shell is used in investment casting. The 3D printing method is also used in manufacturing an article from starch powder.
The 3D printing method needs a post-processing step for increasing the density and the strength. During the post-processing step, there must be thermo-contraction and/or thermo-deformation.
SFF using a layered material is realized with a laminated object manufacturing (LOM) method, which is used by HELISYS Co. The LOM method comprises adhering laminated papers using a heated roller, and the cutting out the papers by a laser beam. Although the LOM method uses paper that is a relatively cheep material, it takes very much time to draw out a finished 3D model or article from a bulk of refuse. In other words, when manufacturing a sphere, it is very bothersome to remove wastes surrounding the sphere after completing to forming it.
These shortcomings are still remained in SFF using plastic laminates, which are recently developed.
STRATASYS Co. uses a fused deposition modeling (FDM) method, which comprises passing a plastic filament through a heat nozzle, which has a similar shape with an extruding mold, so that the filament is melted and cohered. A model or article is very rough because of beads of melted plastic filament.
Hereinafter, SFF for a structural member of metal or a metal mold will be explained.
A laser engineered net shaping (LENS) method developed by SANDIA NATIONAL Lab. and practiced by OPTOMEC Co. comprises partially heating a metal substrate by a laser beam to a melt pool, and then depositing metal powder dispersed in a gaseous body.
The LENS method cannot guarantee a precise size because of deformation on solidifying the melt. Furthermore, it is not able to apply the LENS method to manufacturing an article having protrusions or cantilevers, which cannot receive the melt pool.
A shape deposition manufacturing (SDM) method developed by STANFORD Univ. and CARNEGIE MELLON Univ. comprises a metal depositing step and a computer numerical control (CNC) machining step. The SDM method is practiced by depositing a metal melt on a portion, machining to obtain desired thickness and shape by multi-poled CNC milling, depositing a metal melt on another portion, machining again to obtain desired thickness and shape, and then alternately repeating operations of depositing and machining to complete a layer of metal. After completing the layer of metal, shot peening is conducted to relieve remaining stress. These operations are repeated up to forming a wanted shape. Because of these repeated operations, it takes very much time to manufacture a 3D model using the SDM method.
This invention proposes a novel method for practicing the variable deposition manufacturing (VDM).
The inventive method significantly enhances accuracy of the size and the shape of manufactures, and shortens the time of operation. The method comprises depositing a metal or non-metal material melted by an electrical melting device under the control of a variable nozzle, which has variable thickness, variable width and variable inclination.
According to this invention, a method for manufacturing a 3D model is provided. The method comprises steps of designing the 3D model and collecting shape data of the 3D model slicing the 3D model into several layers with thickness in height, dividing each of the layers into several sublayers so that a sublayer is formed by depositing a material at once, depositing a material using variable nozzle in accordance with shape data in relation to a sublayer divided from one layer of the 3D model, and deciding whether the one layer of the 3D model has been completed. If the result of decision is xe2x80x9cNOxe2x80x9d, the aforementioned steps are repeated for another sublayer divided from the one layer of the 3D model. If the result of decision is xe2x80x9cYESxe2x80x9d, it is decided whether the 3D model has been completed. If the result of decision is xe2x80x9cNOxe2x80x9d, the aforementioned steps are repeated for another layer sliced from the 3D model until the 3D model is completed.
The method may further comprise steps of deciding whether any sublayer has to be supported by a support, and if a sublayer requires a support, positioning the support and adding shape data of the support to the shape data of the 3D model.
According to another aspect of this invention, there is provided a computer-aided design and computer aided manufacturing system used in manufacturing a 3D model by depositing a material in accordance with shape data of the 3D model using a variable deposition manufacturing apparatus that comprises a material feeder, an electrical melting device, a variable nozzle 15 moved by a three-dimensional moving mechanism, and a turntable adapted for rotating the 3D model. The system comprises a main processor for designing the 3D model and collecting shape data of the 3D model, slicing the 3D model into several layers with thickness in height, and dividing each of the layers into several sublayers so that a sublayer is formed by depositing a material at once, a material-feeding controller for controlling the material feeder to adjust the quantity of material fed to the electrical melting device, a nozzle controller for controlling a material ejection from the variable nozzle, a model position controller for controlling operation of the three-dimensional moving mechanism, and the main processor adapted for transmitting the shape data to the material-feeding controller, the nozzle controller and the model position controller so that these three controllers cooperate to form the 3D model.
According to another aspect of this invention, there is provided a variable deposition manufacturing apparatus used in manufacturing a 3D model by depositing a material using a variable nozzle in accordance with shape data of the 3D model. The apparatus comprises a material feeder for feeding a material used in forming the 3D model, an electrical melting device for melting the material, the electrical melting device connected to the material feeder through a conduit, a variable nozzle adapted for depositing the melted material in accordance with shape data of the 3D model, the variable nozzle connected to the variable nozzle through a flow controller, a three-dimensional moving mechanism for moving the variable nozzle in relation to the 3D model, and a turntable adapted for rotating the 3D model.
The apparatus may consist of one or more depositing lines, in which each of the depositing lines has the material feeder, the electrical melting device and the variable nozzle, respectively.
It is preferred that the apparatus further comprises a nozzle heater for preventing a melt in the variable nozzle from being solidified.
The three-dimensional moving mechanism may comprise a slider moved on a Y-directional rail, the first slide adapted to clamp the variable nozzle thereto, a pair of sliders moved on a pair of X-directional rails, the pair of sliders moving the Y-directional rail in X-direction, and one or more sliders moved on one or more Z-directional rails, the one or more sliders moving the turntable in Z-direction.
Preferably, the variable nozzle consists of two parts and connected by a pivot with each other, in which a downstream part of the two parts is adapted to around the pivot to adjust an angle in relation with an upstream part of the two parts, by which an ejection angle of the downstream part is adjusted.
The downstream part of the variable nozzle may comprise a thickness-adjusting panel adapted to be moved upward or downward to adjust the thickness of material ejected from the downstream part, two width-adjusting panels adapted to be moved rightward or leftward to define right and left ends of an outlet of the downstream part of the variable nozzle, and two slope-adjusting panels adapted for defining slopes of the right and left ends of the outlet of the downstream part.